1. Field of the Invention
This invention relates to an apparatus for controlling the infusion of fluids under pressure, including medical solutions and drugs. In particular, the present invention relates to a multi-valve infusion manifold having a plurality of inlet lines, a mixing chamber, and at least one outlet line; the manifold is used to administer a combination of fluids and drugs, such as anesthetics or cardiovascular medications, to a patient.
2. Description of the Prior Art
When it is necessary to administer a combination of drugs to a patient during a controlled medical procedure, such as anesthetizing a patient prior to and during surgery, or maintaining a patient on a combination of drugs during his stay in a cardiovascular care or intensive care unit, the known devices have substantial disadvantages.
For example, it is known to administer a combination of selected drugs by individual syringes, with each syringe connected to a stopcock which in turn is connected with a single primary IV set. In one known device, each stopcock has a control level which must be selectively and sequentially manually rotated to administer the desired combination of drugs to the patient. The level of accuracy associated with infusion rates and drug proportions associated with the aforementioned procedure is highly dependent on the skill of the attending medical professional. Potent anesthetic drugs must be precisely and accurately delivered, to avoid adverse effects on the patient. Other similar devices may use a manual stopcock in combination with a back check valve instead of a control lever.
Another manifold apparatus discloses a cannula assembly that includes a housing defining a fluid flow passage having two fluid inlets and one fluid outlet. One of the fluid inlets is shaped to receive the tip of an injection syringe for introduction of fluid to the inlet. Fluid flow through the inlet is controlled by a check valve housing an elastic tubular valve member closing off outlet openings associated with the check valve. Under sufficient pressure of a fluid in the inlet, the tubular valve member deflects outwardly permitting flow through the outlet openings.
A significant problem associated with such devices is back flow, which permits a solution in a delivery line to enter an adjacent delivery line, to produce an undesirable and unintended admixing of fluids within the input lines.
Further, each apparatus described above employs a multiplicity of parts. A multiplicity of parts makes each of the devices described above prone to unintentional leakages due to many fitment connections. In a multi-valve manifold, each valve may have a pre-set "cracking" pressure, which is normally the same for each inlet valve of the manifold. Cracking pressure is defined as the minimum pressure which opens the inlet valve.
Accordingly, it is desirable to provide an improved multi valve manifold which minimizes backflow, i.e., retrograde infusion or crosstalk from one inlet to another at the inlet valve locations. Further, it is desirable to provide a multi-valve manifold having substantially fewer parts than known devices, thus to minimize inadvertent leakage occurring at connections. Moreover, it is desirable to provide, within the constraints of a simplified manifold structure, means enabling variable pre-set pressure settings at each valve inlet. Such improvements would increase the effectiveness of the manifold, reduce its cost, and minimize the disadvantages and inefficiencies present in known devices.